Ambulance Prior Authorization

Published 12/05/2022

Prior authorization is a process through which a request for affirmation of coverage is submitted for review before a service is rendered to a beneficiary and before a claim is submitted for payment. Prior authorization helps ensure that applicable coverage, payment and coding rules are met before services are rendered. Prior authorization does not create new clinical documentation requirements. Instead, it requires the same information that is already required to support Medicare payment, just earlier in the process. 

Prior Authorization for Repetitive, Scheduled, Non-emergent Ambulance Transport

The Centers for Medicare & Medicaid Services (CMS) implemented the Repetitive, Scheduled, Non-emergent Ambulance Transport (RSNAT) Prior Authorization (PA) model in 2014 for limited states and expanded the model to additional states in 2015. The model was successful in reducing RSNAT services and total Medicare spending while maintaining overall quality of, and access to, care. The model met all expansion criteria and CMS expanded the RSNAT Prior Authorization model for all U.S. states and territories by August 2022.

The RRB SMAC implemented the RSNAT PA model for Railroad Medicare beneficiaries nationwide for transports on and after August 1, 2022.

Repetitive Ambulance Transports 
Repetitive ambulance services are defined as medically necessary ambulance transport furnished in three or more round trips during a 10-day period, or at least one round trip per week for at least three weeks. 

Ambulance Benefit
Prior authorization for RSNAT does not change the Medicare ambulance benefit for non-emergent ambulance transports and does not change the documentation requirements for repetitive, scheduled, non-emergent transports. 

The Medicare ambulance benefit for nonemergent transports is limited to patients who are clinically unable to be transported by other means. Under 42 Code of Federal Regulations (CFR) 410.40(e), Medicare covers ambulance services for patients when:

  • The medical condition is such that other means of transportation is a risk to health
  • Both the ambulance transportation itself and the level of service provided (for the billed service) is considered medically necessary
  • The transport is for a Medicare covered service at a covered destination, or return from a Medicare covered service

For non-emergent repetitive transports scheduled on and after August 1, 2022, ambulance suppliers can request prior authorization for up to 80 trips (equivalent of 40 round-trips) in a 60-day period per prior authorization request.

Prior authorization should ideally be requested prior to rendering transports. Claims for the first three round trips are permitted to be billed without prior authorization to allow time to submit the prior authorization request and obtain approval.

Prior authorization for RSNAT is voluntary. However, if an ambulance supplier elects not to submit a prior authorization request before the fourth round-trip in a 30-day period, the RSNAT claim will be subject to a prepayment medical review.

Submission Methods
Submit your prior authorization request package to Railroad Medicare by one of the following methods:

  • Palmetto GBA eServices portal — this is the preferred method 
  • Fax to (803) 462–2632 
  • U.S. Mail to:

PO Box 17089
Augusta, GA 30903-0001 

  • Electronic submission of medical documentation (esMD)

If you submit your PA request package by fax, mail or esMD, please complete and include a Railroad Medicare Prior Authorization Request form. Completing this form will help ensure we have all the information needed to complete your request. 

Documentation Requirements
In addition to the information required on the Prior Authorization Request form, your request must contain the following:

  • Physician Certification Statement — completed and dated with the signature and credentials of the certifying physician
  • Current documentation from the medical record to support the medical necessity of the transports
  • Information on the origin and destination of the transports 

See our article Requesting Prior Authorization for Repetitive, Scheduled Non-Emergent Ambulance Transports for details about when, how and what to submit with a RSNAT PA request and information about what to do after your receive a PA decision. 

General Facts About the Program


Independent ambulance suppliers that are not institutionally based providing Part B Medicare covered ambulance services billed on a CMS-1500 form and/or a HIPAA compliant ANSI X12N 837P electronic transaction.


Ambulance suppliers can request and receive prior authorization for up to 40 non-emergency scheduled round trips (which equates to 80 one-way trips) per prior authorization request in a 60-day period.

For scheduled trips beyond the prior authorized number, a second prior authorization request is required.

PA can be requested for the following Healthcare Common Procedure Coding System (HCPCS) codes: 

  • A0426 — Ambulance service, advanced life support, non-emergency transport, level 1 (ALS1)
  • A0428 — Ambulance service, basic life support (BLS), non-emergency transport

Associated service HCPCS code A0425 (Ground mileage, per statute mile) should be billed with the appropriate transport code but is not subject to prior authorization. 

Prior authorization cannot be requested for any other HCPCS codes.


For transports of Railroad Medicare beneficiaries scheduled on and after August 1, 2022.


Any U.S. state or territory.


Helps ambulance suppliers ensure that their services comply with applicable Medicare rules before services are rendered and before claims are submitted for payment.


Submit the prior authorization request to Palmetto GBA Railroad Medicare. Attach all required documentation.

  • Decision notifications will be issued within 10 business days of receipt of submission
  • Resubmission decision notifications will be issued within 10 business days of receipt
  • The notification letter will contain a 14-digit unique tracking number (UTN) that must be submitted on applicable claims
    • Paper Claims – Submit the UTN in the first 14 postitions in Item 23 of the CMS 1500 claim form. All other data submitted in item 23 must begin in position 15.
    • Electronic Claims – Submit the UTN in either the 2300 - Claim Information loop or 2400 - Service Line loop in the Prior Authorization reference (REF) segment where REF01 = “G1” qualifier and REF02 = UTN

We will share information on this page to keep you informed about the program. Visit this page often and please be sure to register to receive Email Updates. Access CMS RSNAT PA resources directly on the Prior Authorization and Pre-Claim Review Initiatives page.

The CMS Repetitive, Scheduled Non-Emergent Ambulance Transport Prior Authorization Model Operational Guide (PDF) provides operational details about the RSNAT Prior Authorization model.

Additionally, ambulance suppliers can share an Ambulance Prior Authorization Physician/Practitioner Letter (PDF) with physicians and other entities to help ensure that they obtain the necessary documentation in a timely manner.

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